Electronic Components Datasheet Search |
|
REF3140 Datasheet(PDF) 7 Page - Burr-Brown (TI) |
|
|
REF3140 Datasheet(HTML) 7 Page - Burr-Brown (TI) |
7 / 11 page REF3112, 3120, 3125, 3130, 3133, 3140 7 SBVS046A www.ti.com THEORY OF OPERATION The REF31xx is a family of series, CMOS, precision bandgap voltage references. The basic bandgap topology is shown in Figure 1. Transistors Q1 and Q2 are biased such that the current density of Q1 is greater than that of Q2. The difference of the two base-emitter voltages, Vbe1 – Vbe2, has a positive temperature coefficient and is forced across resistor R1. This voltage is gained up and added to the base-emitter voltage of Q2, which has a negative temperature coefficient. The resulting output voltage is virtually independent of temperature. 100 µA, and the maximum quiescent current over temperature is just 135 µA. The quiescent current typically changes less than 2 µA over the entire supply range, as shown in Figure 3. 1 3 REF31xx 2 0.47 µF V IN V OUT FIGURE 1. Simplified Schematic of Bandgap Reference. FIGURE 2. Typical Connections for Operating REF31xx. FIGURE 3. Supply Current vs Supply Voltage. R 1 Q 2 Q 1 IN + Vbe 1 – + Vbe 2 – V BANDGAP APPLICATION INFORMATION The REF31xx does not require a load capacitor and is stable with any capacitive load. Figure 2 shows typical connections required for operation of the REF31xx. A supply bypass capacitor of 0.47 µF is recommended. SUPPLY VOLTAGE The REF31xx family of references features an extremely low dropout voltage. With the exception of the REF3112, which has a minimum supply requirement of 1.8V, these references can be operated with a supply of only 5mV above the output voltage in an unloaded condition. For loaded conditions, a typical dropout voltage versus load is shown in the typical curves. The REF31xx features a low quiescent current, which is extremely stable over changes in both temperature and supply. The typical room temperature quiescent current is Supply voltages below the specified levels can cause the REF31xx to momentarily draw currents greater than the typical quiescent current. This can be prevented by using a power supply with a fast rising edge and low output impedance. THERMAL HYSTERESIS Thermal hysteresis for the REF31xx is defined as the change in output voltage after operating the device at 25 °C, cycling the device through the specified temperature range, and returning to 25 °C. It can be expressed as: V abs V V V ppm HYST PRE POST NOM = • ( ) – 10 6 Where: VHYST = Thermal hysteresis VPRE = Output voltage measured at 25°C pre- temperature cycling VPOST = Output voltage measured after the device has been cycled through the specified temperature range of –40 °C to +125°C and returned to 25°C. TEMPERATURE DRIFT The REF31xx is designed to exhibit minimal drift error, defined as the change in output voltage over varying temperature. The drift is calculated using the “box” method which is described by the following equation: VV V TemperatureRange ppm OUTMAX OUTMIN OUT – • • 10 6 The REF31xx features a typical drift coefficient of 5ppm from 0 °C to 70°C—the primary temperature range for many applications. For the industrial temperature range of –40 °C to 125 °C, the REF31xx family drift increases to a typical value of 10ppm. QUIESCENT CURRENT vs POWER SUPPLY 100.5 100.0 99.5 99.0 98.5 98.0 1.5 Power Supply (V) 2.5 3.5 4.5 5.5 |
Similar Part No. - REF3140 |
|
Similar Description - REF3140 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |